1. Field of the invention
This invention relates to a system and process for the treatment of oil sands for the recovery of their petroleum fraction or bitumen.
2. Background Art
Crushed ore of oil sands consisting of bitumen and sand fractions is commonly treated through a water emulsifying process with warm or hot water followed by a vaporization process to extract their bitumen content which is subsequently refined to obtain various petroleum products. Such process is ineffective and costly to carry out due to the demand of a large amount of energy input in the process with a relatively low bitumen output. Chemical material such as sodium hydroxide also has been added into the warm or hot water treatment to increase the amount of bitumen extraction. The water as well as the chemical material discharged from such process are harmful to the natural environment, and the system occupies a large erection site.
A mechanical shearing method has also been employed to de-aerate the slurry of water and oil sands mixture for extracting the bitumen. The slurry is passed through a shearing impeller operated at various high speeds in a treatment tank. In such mechanical shearing process, sand and water settle to the bottom of the tank while the bitumen content is collected in the froth in the top portion of the tank. The process may be repeated in a plurality of tanks to remove further the water and sand contents. However, this method is also ineffective and costly to achieve and the removal process is not uniform and limited and it would rapidly reach a steady saturated level with little increase in the bitumen extraction in the repeated process.